Since a week or two my bitcoind was looping, syncing100% then back to 99.xx% in an infinite loop.
Today, while looking at tail -f /home/umbrel/umbrel/app-data/bitcoin/data/bitcoin/debug.log Tadaa !!
Enlarge your cache is the way : from 512 to 800Mb and it works…
Bitcoin Core 27.0.0 / umbrelOS 1.2.1